Many reports about Venus refer to the cat as a "chimera." In mythology, a chimera is a mishmash monster made up of parts of different animals. A feline chimera is a cat whose cells contain two types of DNA, caused when two embryos fuse together.

Among cats, "chimeras are really not all that rare," Lyons said. In fact, most male tortoiseshell cats are chimeras. The distinctively mottled orange and black coat is a sign that the cat has an extra X chromosome.

But female cats, said Lyons, already have two X chromosomes so they can sport that coat without the extra X. That means Venus is not necessarily a chimera.

To find out would require genetic testing, said Lyons. With samples of skin from each side of the cat, "we can do a DNA fingerprint—just like on CSI—and the DNA from one side of the body should be different than the other."

If Venus isn't actually a chimera, then what would explain her amazing face?

"Absolute luck," Lyons said. One theory: perhaps the black coloration was randomly activated in all the cells on one side of her face, while the orange coloration was activated on the other, and the two patches met at the midline of her body as she developed.

Cat fanciers who are transfixed by Venus's split face may be missing the real story: her single blue eye. Cat eyes are typically green or yellow, not blue. (Take a cat quiz.)

A blue-eyed cat is typically a Siamese or else a cat with "a lot of white on them," she explained.

Venus appears to have only a white patch on her chest, which to Lyons is not enough to explain the blue eye.